The present invention relates to a method for restoring the buffer coating or jacket on an ultraviolet (UV) light curable resin coated optical fiber at a fusion splice.
In considering splicing as a means to achieve long lengths of strong fiber, one restriction can be addressed immediately. Since the spliced region must be handled in cabling, precision winding or in payout in exactly the same way as the rest of the optical fiber, the finished splice, including jacket repair, must conform to the original fiber in physical dimensions as well as flexibility. This precludes the use of stiffeners in the spliced region, including hard epoxy masses or stainless steel tubes. Because of the strength requirements, only methods of directly fusing the fibers together for the splicing arrangement can be considered.
In order to meet or attain the desired performance from the spliced fiber, the splice must be rejacketed with the original jacket material with certain constraints placed on the rejacketed splice dimensions. In the case of fibers used for precision winding, such as rapid payout fibers for missile guidance, the splice must be as close as possible, but not greater than the original jacket outer diameter. Oversized splices will disturb the precision winding for all winding layers above the splice. Small voids can be tolerated over the short length of a splice (less than 15 mm) because a void filling compound is typically used in the precision winding process.
Devices or techniques used to rejacket the splices in the past have included a precision injection mold, a precision casting mold, or a simple dip coat. These devices or techniques work well with heat cured material. However, UV cured resins require a UV transparent mold. Also, injection or casting molds leave some form of flash or excess material on the splice which must be removed in a separate process step, often resulting in a loss of precision diameter control. Also, precision injection molds or casting molds do not compensate for changes in fiber diameter, i.e. these molds have a fixed size.